For each of the following transactions, state which account(s) would be debited and credited in a job

Question:

For each of the following transactions, state which account(s) would be debited and credited in a job order costing system:
a. Purchased materials on account, $12,000.
b. Charged direct labor to production, $3,000.
c. Requested direct materials for production, $6,000.
d. Applied overhead to jobs in process, $4,000